Handheld electronic devices have benefited from touch screen technology. Touch screens are used for both input and output. They enable device manufacturers to reduce the area of the device used for off-screen input controls, such as buttons and keypads, and to enlarge the screen area, thereby enhancing the user experience.
For input, users interact with touch screens using visual control elements. Control elements correspond to user commands, are displayed on a screen, and provide areas for a user to press on. Control elements may appear as buttons, scroll bars, slide bars and wheels. Users can press or tap on control elements such as buttons, or drag control elements such as scroll bars, slide bars and wheels to a desired location. Pressing, tapping or dragging control elements activates their corresponding commands.
For output, touch screens display graphics, similar to conventional LCD displays.
Reference is now made to FIG. 1, which is a prior art illustration of a touch screen. Shown in FIG. 1 is a handheld electronic device 100 having a touch screen 110. Device 100 displays various buttons 120 in touch screen 110, which a user can press in order to enter numbers and commands.
An advantage of touch screens is the flexibility of displaying a wide variety of control elements, such as buttons, icons and selection menus, for a corresponding wide variety of modes of operation. Thus, while in a dialer mode of operation, a touch screen may display a numeric keypad, and while in an SMS mode of operation, the touch screen may display an alphabet keypad. Areas on the screen thus produce different actions when pressed, depending on the control elements being displayed therein.
A drawback with touch screens is the lack of a tactile feeling, as a result of which many people find them difficult to use. Prior art methods of overcoming this drawback include graphical methods, audio methods, force feedback methods and vibration methods. Graphical methods make control elements appear to be pressed and released, similar to physical buttons presses, thus creating a perception of a physical button press. Audio methods provide sounds in response to elements being pressed. The TouchSense® system of Immersion Corporation of San Jose, Calif., includes both graphical and audio feedback when touch screens are pressed.
Force feedback methods operate by mounting a touch screen on a linear flexure, which allows the screen to bend inwards when pressed. Force feedback for touch screens is described in U.S. Pat. No. 7,113,177 to Franzen. The '177 patent describes a touch-sensitive display with tactile feedback, comprised of three layers; namely, a display layer, a layer that includes receptors, and a layer that includes controllable actuators.
Vibration methods cause a device to vibrate in response to a control element being pressed, as a tactile feedback. Pantech Group of Seoul, Korea, developed such a touch screen for its dual-LCD sliding phones.